Turbine construction



Feb. 21, 1961 H. L. MCCORMICK 2,972,470

' TURBINE CONSTRUCTION Filed Nov. 3, 1958 2 SheetsSheet 1 X INVENTOR.

1961 H. L. MCCORMICK 2,972,470

TURBINE CONSTRUCTION I Filed Nov. 3, 1958 2 Sheets-Sheet 2 A T TOR/V5)TURBINE CONSTRUCTION Hamilton L. McCormick, Carmel, Ind., assignor toGeneral Motors Corporation, Detroit, Mich., a corporation of DelawareFiled Nov. s, 1958, Ser. No. 771,337

s Claims. (Cl. 25349 This invention relates to a turbine assembly for agas turbine engine.

More specifically, this invention relates to the construction of aturbine in a manner to permit removal of the turbine blades thereinwithout disassembly of the turbine rotor.

In many constructions of a turbine, upon rupture or breaking of any oneof the turbine blades therein, it becomes necessary to disassemble theentire turbine in order to remove that particular blade. From abalancing stand point, once the turbine rotor is disassembled, theentire turbine must be rebalanced upon reassembly, which is an expensiveand tedious procedure. I

This invention eliminates rebalancing of the turbine rotor byconstructing the turbine in a manner such that any one or a number ofthe turbine blades therein may be removed without-disassembling theentire rotor. enables the manufacturer to replace the blade or bladeswith blades of equal weight, thereby maintaining the turbine balancedboth statically and dynamically.

This invention accomplishes the above objective by mounting the turbineblades and'interstage spacers on the turbine disks or wheels and spacerdisks by means of firtree inserts so as to permit axial sliding movementrelative thereto. Furthermore, axial positioning flanges are provided onportions of the turbine blades, rotor wheels and interstage spacers,preventing axial movement in one or both directions. The construction issuch that it is necessary to remove only one end connection to removeone or'a row of rotor blades from the assembly. With the one rowremoved, removal of the stator vanes, interstage spacers, and otherstage turbine blades is easily accomplished upon removal of thecorresponding portions of the engine casing.

Therefore, it is an object of this inventionto provide a turbineconstruction permitting removal of any of the rows of turbine bladeswithout disassembly of the turbine rotor.

Other features, advantages and objects will become apparent by referenceto the detailed description of the invention and to the drawings whereinthere isshown the preferred embodiment of this invention.

In the drawings:

Figure l is a partial cross-sectional view of a turbine embodying thisinvention,

Figure 2 is a cross-sectional view on a reduced scale of a portion ofthe turbine of Figure 1 showing the turbine in partially disassembledcondition,

'Figure 3 is a cross-sectional view of a detail viewed by passing aplane through the lines indicated by the arrows 3-3 in Figure 1, and

Figure 4 is a cross-sectional view similar to Figure 3 obtained bypassing a plane through the lines indicated by the arrows 44 in Figure1.

Referring now to the drawings and more particularly to Figure l, aturbine assembly is" shown comprising in general an outer turbine casingsupporting a plurality of annular axially spaced stator vane assemblies12, 14

and 16 cooperating with first, second and third stage an- This StatesPatent O nular rotor blade assemblies 20, 22 and 24 axially spaced fromeach other by annular interstage spacer assemblies 26 the turbine casecomprises a plurality of axially aligned circular casing portions 32, 34and 36 suitably connected together at their abutting flanged edges 40and 42 by a plurality of circumferentially spaced bolts 44 (only one setshown). Supported from the casing sections by means to be described arethe stator vane assemblies 12, 14 and 16, each consisting of an outershroud ring 46, 48 and 50, respectively, to which are welded orotherwise suitably secured a plurality of circumferentially spacedstator vanes 52, secured at their tip portions to an inner shroud 54, 56and 58, respectively. Each of the radially outer shrouds 46, 48 and 50comprises a number of arcuate abutting sections, preferably six, forexample. The radially inner shrouds 54, 56 and 58 of assemblies 12, 14and 16 also each consist of six ribbed abuttingsegments of a shroud ringwelded to the tips of each of the stator vanes, the segments togetherforming a substantially continuous annular surface. I

The stator vane assemblies are supported from and connected to theengine casing portions 32, 34 and 36 by suitable tongue and grooveconnections as shown formed on the casing portions and'outer shroudrings, the outer shroud rings 46 and 48 of assemblies 12 and 14 havinginterfitted therebetween a ring member 60 constituting the first stagerotor blade shroud ring. Ring member 60, and shroud rings 46 and 48 aresecured in position and supported from the casing by a number ofcircumferentially spaced dowels 62.

Also supported from the engine casing 10 by an annular bulkhead 64connected to an annular stepped'supporting strut 66 is the bearing 11rotatably supporting the turbine drive shaft 30.

Referring now to the details of the turbine rotor cooperating with thestator vane assemblies, the rotor is of the axial flow type having threestages 20, 22 and 24 comprising rotor wheels or disks 68, 70 and 72,each having secured thereto at its outer periphery by conventionalfirtree insert and slot means 74 and 76, respectively (Figs. 24),'anumber of circumferentially spaced rotor blades 78 provided withplatforms 80. The hub portions 82, 84 and 86 of rotor wheels.68, 70 and72 consist of axially aligned-stub sleeve shafts formed integral withthe wheels, and abutting each other at adjacent edges.

Inserted between the first and second stage rotor sleeve shafts S2 and84 is an. end flange 88 of the turbine drive shaft 30, the three sleeveshafts and drive shaft flange being fixedly secured together by a numberof circumferentiallyspaced tie-bolts 90 insertable through suitableapertures therein. Although any number of tie-bolts may be used,preferably ten, for example, would be preferred in the constructionshown.

The construction above described explains the manner of axially locatingthe stator vane assemblies, and the manner in which the stator vane androtor blade assemblies are-located radially with respect to each other.The axial disk 94 has a similar tongue and; groove support connec tion97 with the hubs s4 and 86. measures-rotation of the disks 92 and 94with the turbine rotor upon tightening of the tie-bolts 90. The radiallyouter portion of each of the disks 92 and 94 is U or channel-shape asshown in Figure 2 and formed with a number of circumferentially spacedaxially extending fir-tree slots 98. Cooperating with slots 98 are aplurality'of mating fir-t-ree inserts 99 provided on each of two axiallyspaced annular flanges 100 suitably secured to or formed integral withan annular rim 102, the slots and inserts being equal in size andnumberrto the number of third stage rotor blade inserts 74 for removalpurposes as will be described, and the rims 102 cooperating with theradial ribs of shroud rings 56 and 58 to form labyrinth motive fluidseals. Each of the rims 102 is provided with radially outwardlyextending parallel flanges 104 and 106 adapted to abut the adjacentedges 108 and 110 of the platforms of the first and second and secondand third stage turbine blades, respectively. The turbine rotor bladeassemblies are thus axially spaced from each other by the spacer diskshroud rims 102.

Depending from each of the fir-tree formed rotor blade inserts 74 at itsdownstream edge as seen in Figures 3 and 4 is a flange 112 overhangingthe edge of the rotor wheel with which it is associated for furtheraxially locating the rotor blades, the flanges 113 on the third stageblade inserts 74 being somewhat larger and further extended for apurpose to be described hereinafter. The spacer disks 92 and 94 and rims102 are likewise axially located in one direction with respect to eachother by depending flange portions 114 secured to each ofthe fir-treeinsert portions 99 on the downstream leg of tang portions 100 to overlapthe annular leg 115 of the U-shaped spacer disks 92 and 94. To axiallyposition the assembly at each end thereof, the first stage rotor wheel68 has secured thereto by a number of circumferentially spaced bolts116, the rotating portion 118 of an annular triple interstage labyrinthseal number 120 cooperating with a stationary portion 122 of the sealsecured to bulkhead 64. Seal portion 118 is abutted at 124 by adepending flange 126 secured to the platform 80 of each of the turbineblades 78. At the downstream end of the the turbine assembly, the thirdstage rotor wheel 72 is provided at its downstream edge with an annulardepending flange 132 of the same radially inward extent as flanges 113on the turbine blade fir-tree'inserts 74. Connecting the flangestogether to prevent axial movement between the stalk and the rotor wheelin either direction is an annular expanding type snap ring 134 providedwith radial flanges 136 surounding the flanges 132' and 113. With theconstruction as described, the rotor blade and stator vane assembliesare both axially and. radially fixed with respect to each other.

The turbine rotor is assembled separately as a unit prior to insertionin the engine casing by axially aligning the three rotor wheels 68, 70and 72, the spacer disks 92 and 94, and the extension 88 of the turbinedrive shaft in the correct order, and joining them together by thetie-bolts 90; The individual rotor blades 78 of the first stage are thenpositioned in place by a meshing of the fir-tree inserts 74 with theslots 76 in the rotor wheel 68, the flange portions 126 on the bladeplatforms 80 abutting the seal portions 118, and the. flange 112abutting the wheel 68 for axially locating the blades. Spacer rim 102and flanges 100 are then slid into position on spacer disk 92 as shownso that flange 104 abuts, edges 108 of platforms 80, and flanges 114abut the spacer disk 92. The second stage turbine blades aretheninserted into the second stage wheel 70 with each of the platform edges'110 abutting flange 106 and flanges 112 abutting wheel 70. Spacer rim1'02 and tangs 100 are then. slid into engagement with spacer disk 94,with the flange 104 abutting platforms 88 of the second stage rotorblades and flanges 114 abutting spacer disk 94. Theinserts 74 of thethird stage rotor blades 78 are then engaged with the fir-tree slots 76'of the wheel 72 and the flanges 113 and 132 and flange and platformedges abutted. Finally, the expanding snap ring 134 is inserted tofasten the flanges 113 and 132 together, and the turbine rotor assemblyis complete. The rotor assembly is thus prevented from axial movement asseen in Figure 1 by the abutment of flange 126 on the blade platform 80of the first stage turbine assembly 20 against the seal portion 118, theholding of the last stage turbine blade assembly from axial movement ineither direction by the expanding snap ring 134, and the interstagespacer disk rims 102 axially positioning the first, second and thirdstage rotor blade assemblies. The assembled rotor is then balanced bothstatically and dynamically before being inserted in the engine casing.

The assembly of the eomplete turbine is then as follows. The turbine isassembly by placing the sections on end and building up as would beviewed from the bottom of Sheet 1 of the drawings. The circular casingsection 32 together with the abutted segments of the first stage statorvane assembly 12, bulkhead 64, labyrinth seal portion 122 and bearing 11are positioned in place. a

The assembled rotor is then slid into place with the turbine shaft 30being inserted though bearing 11 to be rotatably supported thereby, andthe rotating portion 118 of seal positioned in place adjacent sealportion 122. The first stage rotor blade shroud ring 60 is then placedin position on top of shroud 46 (as viewed from the bottom of Sheet 1containing Figure 1) and located by dowels 62. The six segments of thesecond stage stator vane assembly -14 are then laid in place, and theengine casing section 34 is then-positioned in place; and bolted tovsection 32. at 40- by suitable bolts (not shown). I The segments of thethird stage stator vane assembly 16 are then mounted on casing 34, andthe. final turbine casing section 36 is fitted over shroud 50 andsecured to casing section 34 by bolts 44. The assembly of the entireturbine is then complete. It is to be noted that, as assembled, thesubstantially continuous fairing of the several stages consisting of theblade platforms 88 and the inner and outer'shroud rings of the statorvane assemblies provides a streamlined path for the flow of motive fluidthrough the turbine. Furthermore, thev labyrinth seals formed-bythe rims102 and the inner shroud rings 56, and 58 cooperate with the labyrinthseal 120 and blade platforms to. prevent the hot, motive fluid fromreaching the bearings and the radial inward portions of the turbine,which would be injurious thereto.

To disassemble, as seen partially in Figure 2, all that is necessary isto remove the expanding snap ring 134, slide the third stage rotorblades 78 axially, remove bolts 44, the casing section 36, and thethird. stage stator vane assembly 16, axially move the second-thirdstage spacer rim 102, axially slide the second stage rotor blades 78,remove turbine casing 34 together with second stage stator vane assembly14, axially remove the first-second stage spacer rim 102, and thenremove the; first stage turbine blades 78. Thus, the blades or vanes ofany stage may be removed without disassembling the turbine rotor.

From the foregoing it will be seen that this invention provides aturbine construction permitting the removal of any of the turbine bladeswithout disassembly of the turbine rotor, thus maintaining the dynamicand static balance of the rotor. Any of therblades may be replaced withblades of equal'weight thus eliminating the necessity ofrebalancing theentire turbine assembly.

While the preferred embodiment of this invention has been illustrated inconnectionwith a turbine of a gas turbine engine, it will be clear' tothose skilled in the art that many modifications can be made theretowithout departing from the scope of the invention.

I claimt 1. A turbine assembly for a turboma'chine having a stationarycasing comprising a multi-disk turbine rotor, said rotor including aplurality of axially spaced and aligned turbine blade support disksthereon, a plurality of circumferentially spaced turbine blades axiallyslideably secured to each of said disks, annular spacer disks mounted onsaid rotor between said support disks, said spacer disks having axiallyextending spacing means axially slideably mounted thereon having theiraxial edges abutting adjacent turbine blades for axially locating saidturbine blades with respect to each other, removeable means engaging oneof said support disks and the said turbine blades associated therewithsecuring them together against axial movement therebetween in eitherdirection, means between said blades and disks preventing axial relativemovementin one direction, removal of said removeable means permittingaxial removal of said turbine blades in the other direction withoutdisassembly of said rotor.

2. A turbine assembly including a multi-staged axial flow type turbinerotor including a plurality of axially spaced and aligned turbinewheels, means securing said wheels together, a plurality of turbineblades axially slideably secured to each of said wheels, spacer meansmounted on said wheels therebetween and having portions axiallyslideably secured thereto, means securing said blades to said wheelsagainst axial movement in one direction, a stationary casing surroundingand enclosing said turbine blades and said rotor, said spacer meansportions abutting the blades of axially adjacent stages for axiallypositioning said blades, means on said casing adjacent one end of saidassembly abutting one stage of said blades, and removeable means at theother end of said assembly secured to one of said wheels and the bladesassociated therewith preventing axial move ment therebetween, removal ofsaid removeable means and said casing permitting the slideable axialremoval of said turbine blades and spacer portions from said wheels inthe other direction.

3. An axial flow type turbine assembly comprising a stationary axiallyextending casing, a plurality of axially spaced and aligned rows ofstator vanes removably secured to said casing, a plurality of axiallyspaced and aligned rows of turbine blades positioned between the rows ofstator vanes for cooperation therewith, a turbine rotor comprising aplurality of axially spaced turbine wheels, means securing said wheelstogether, fastening means on said turbine blades and said wheelscooperating together for axially slideably securing said blades to saidwheels, means between said blades and wheels axially locating saidblades with respect to said wheels in one direction, spacer diskssecured to and between said wheels having axially spaced portionsaxially slideably secured thereto having edges abutting the blades onaxially adjacent wheels, and means removeably secured to one of said rowof blades and one of said wheels preventing axial movement therebetweenin either direction, removal of said last mentioned means and saidcasing permitting the axial removal of all of said turbine blades andsaid spacer disk portions in the other axial direction withoutdisconnection of said turbine wheels.

4. A turbine assembly having a multi-staged axial flow rotor comprisinga plurality of axially spaced and aligned turbine wheels, means securingsaid wheels together for simultaneous rotation, a plurality of turbineblades axially slideably secured to each of said wheels, spacer meanssecured to and between said wheels for rotation therewith, said spacermeans having axially extending flanges axially slideably secured theretoand extending between axially adjacent blades for axially spacing theblades on one wheel with respect to the blades on an adjacent wheel,means on said blades and said wheels engageable with each other forremovably securing said blades to said wheels and preventing axialmovement therebetween in one direction, and means secured to the bladessecured to one of said wheels and to said wheel preventing axialmovement therebetween in both directions, removal of said last mentionedmeans permitting the axial removal of all of said turbine blades andspacer flanges in the other axial direction without disconnecting saidturbine wheels.

5. A multi-stage axial flow turbine assembly including a removeablestationary axially extending casing having a plurality of axially spacedand aligned rows of stator vanes removably secured thereto, a turbinerotor having a plurality of axially spaced and aligned turbine wheelssecured together for simultaneous rotation, a plurality of rows ofcircumferentially spaced turbine blades axially slideably secured tosaid wheels between said rows of stator vanes, a plurality of spacersupport means secured to said wheels for rotation therewith andpositioned axially therebetween, said support means having outer annularrims axially slideably secured thereto, said rims each having axiallyspaced edge portions abutting the blades of adjacent stages to axiallylocate said blades with respect to each other, means on said wheels andsaid rotor blades and said spacer means and said rims, respectively,engageable with each other for axially positioning said blades andwheels and spacer means and rims with respect to each other, andremoveable means secured to the blades of one rotor row at one end ofsaid assembly and to the rotor wheel associated therewith preventingaxial relative movement therebetween in either direction, means on saidcasing abutting a rotor blade row at the opposite end of said assemblypreventing axial movement of said wheels, blades and spacer rims in onedirection, removal of said removeable means permitting axial removal ofsaid turbine blades and rims in said other axial direction upon removalof said casing and said stator vanes without disassembly of said rotor.

References Cited in the file of this patent UNITED STATES PATENTS880,479 Buck Feb. 25, 1908 2,241,782 Jendrassik May 13, 1941 2,656,147Brownhill et al. Oct. 20, 1953 2,807,434 Zimmerman Sept. 24, 1957FOREIGN PATENTS $86,561 Great Britain Mar. 24, 1947 1,061,411 FranceNovi25, 1953 1,158,244 France Jan. 20, 1958 UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Patent Nos 2372 470 February 21 1961 HamiltonL, McCormick lt is hereby certified that error appears in the abovenumbered patent requiring correction and that the said Letters Patentshould read as corrected below.

for number read member Column 3 line 37 read W assembled line column 4line 1'6 for "assembly 24L for "though" read through Signed and sealedthis 12th day of September 19610 (SEAL) Attest: ERNEST W. SWIDER DAVIDL. LADD Commissioner of Patents Attesting Officer USCOM M- DC

